Disk harrow



1,670,393 c. H. WHITE DISK HARRow May 22, 1928.

'Original Filed July 5, 1924 4 Sheets-Sheet 2 Uma 17T.

May 22, 1928.

C. H. WHITE DISK HARROW Original Filed July 5, 1924 4 Sheets-Sheet 3 my? Andi imm@ ma@ May22, 1928. 1,670,393

c. H. WHITE DISK HARROW 4 original Filed July 5, 1924 4 sneetssheet 4 lqtranfr C www l uur. lfnrgulf.

WTUass/g Patented May 22, 192s.

UNITED1- STATES PATENT oFFicri. y

CHARLES H. WHITE, 0F MOLINE, ILLINOIS, ASSIGNOR TO DEERE & COMPANY, 0F

. MOLINE, ILLINOIS, A CORPORATION 0F ILLINOIS.

DISK HARROW.

Application nea my 5, i924, serial No. 724,539.' Renewed octane: 2e, 1927.

My invention relates` to tandem disl; har'- rows, or disk harroivs comprising front and rear sections each composed lof a'pair ot' disk gangs so mounted that they may be turned into a: position of alincment 'for traneport purposes, which is their `inoperative position, or may be turned into angular relation to each other, which is their operative i position.

In hai-rows ofthe tandem type the rear section is drawn through `the front section, with which the draft' power, either a team or a tractor, is'connected, and-it has been largely the custom to connect therear section flexibly withv the front section so to permit the front and rear units or sections to swing laterally relatively to each other for convenience in driving around trees or' other obstacles, or in turning corners, Well as to permit.` vertical movement o'l either or both of the rear gangs relatively to the gangs ot the front' objection to flexibly connected tandem dish harrows as heretofore Constructed that they have not been equipped with adequate Imeans for so controlling the position ot thel rear harrow section that each of the disks of the rear gangs will alivays Work in' the ridge left' between the furi'ows. turned by the pair of front disks behind which it is set, or,` in other Words, will not run into or across one of such furrows and thereby leave some portion of they ridge between themunturned. This `relation oi the disks ot' the rear gangs to those of the front gangs may appropriately be termed registration, `and the maintenanc of `registration. in a disk harrovv of the tandem flexibly connected type on straight-away ivorlt, and also When turns are made, so that the ridges lett between the `ront disks will be properlycut at all times, and, in making turns, the rear gangs can! not by swinging in on the turn damage trees or strike obstacles that lhave been avoidedl by the 'front gangs, is a result which those skilled inthe art have for many year-s sought to accomplish, but which prior to the in vention of Frederick E. Hand, for which he has made application for Letters Patent, filedl or even date herewith, has never been realized in a practical' way. ln the operation of flexibly connected tandem dish harrows the front section is steered, and held against any considerable oscillation aboutL y y the point of contact between them hes in a vertical axis, by the draft power, but the section, but a serious rea-i" section, being pivotally connected to" the front section, in the absence of adequate `controlling means is free to` oscillate `oi" swing laterally about a. vertical axis independently of the front section ivhen the disks of theopposite rear gangs encounter unequal y resistance, which swinging shifts the disks troni their normal registering position with relation to the disks of the front gangs. The condition" of an unopposed tendency of the rear harrouT section to so swing later` 'y ally, which maybe termed nervmisness,` l

their registering position, and this is particularly desirable 1n turning, and also in side hill Work, Where al nervous harrovv has a strong tendency to side-slip or drift, and

so get out `ot' registration. Many constructions liave heretofore been proposed to; cure" vthis nervousness and obtain stability, but

While some of such attempt-s have been ineas`-V urably successful so far as relieving nervoiisness' on straii-gl'itavvay Work is concerned, with the exception of said Hand invention it has been done at the expense of flexibility,

and oil maintaining registration on curves, or

on turnsto avoid obstacles'.`

to said Hand invention, the;

According objections to prior constructions arev avoided and the desired results obtainedby causing the draft force to operate as a positive factor in maintaining registration andv overcoming nervousness by opposing oscillation or lat-j` eral swinging of the "rear liarrovv section independently ofl' the frontsection, and by directly aiding in the restoration of the rear `section to its normal operative position when a straight-away course is resumed after a turning movement. In the harroiv y f illustrated and described in said Hand` alpplication, this is accomplished byproviding the iront and rear harrowlunits With 'trans versely disposed curved members in the form of bars secured to or forming a part of the trames of said units respectively, the curved memberA connected `With the front frame being in rearof` that connected with the rear trame, so that a pushing orceis applied to the rear frame by the front frame'. The curved members referred to are convex, and when the hai-row units are in their normal posit-ion, as for straight-away Work,

the median line of the barrow and prefer' ably at a point midway between the transverse axes of said units. By this arrangement when the front unit is turned in either direction, as in turning corners o1' avoiding obstacles. the trai'isverse axes of said units` are angled relatively to each other sothat they converge toward the cellier of the circle along an arc of which the turn is being made, and consequently the disks of the rear gangs may maintain their proper registering relation to the disks of the front gangs. At the same time the point of application of the draft of the rear unit will be shifted inversely laterally or away from the center of the circle, and as in making a turn the center of load represented by the rear unit shifts toward the outside of the curve, the point of application of the draft to the rear unit shift-s in the same direction as the center of load, and the draft therefore operates effectively to restore the rear unit to its normal or straight-away position. In like manner, when the barrow is traveling straight ahead, whenever the rear unit swings laterally with reference to thc front unit., owing to unequal resistance encountered by the disks at opposite sides of the median line of the barrow, the point of contact between said curved members shifts in the same direction as the center of load, or toward the lagging side of the rear unit, and therefore the draft operates to resist such lateral swingingl of the rear unit and to restorejt to its normal position, In the barrow `illustrated in said Hand application the `curved members above referred `to are held against endwise movement with relation to each other, and are also held in engagement with each other when backing the barrow, by means of a pair of crossed links having their rear ends connected with the frame of the front unit and their forward ends connected with the frame of the rear unit, said links being coordinated with the curvature of the curved members so that they do not interfere with their operation in the manner above indicated.

My present invention has to do with a barrow of similar construction to that dis` closed in saidQHand appli ation so far as the useof the curved member is concerned, and it has Afor its object to provide improved means for holding said curved members in proper relation to each other under normal, operating conditions, as well as when backing the barrow. This object I accomplish as illustrated in the accompanying drawings and as hereinafter described. What I regard as new set forth in the claims.

In the accompanying drawings,-

Fig. 1 is a side elevation of my improved barrow with the gangs in transport position;

Fig. 2 is a plan view of the principal parts of the barrow, some parts being the draft connections more in detail in the i position they occupy in the illustration of Fig. 3.

Referring to the drawings,-the barrow therein illust-rated comprises a front or draft frame ,designated as a whole by thc reference numeral G, a front barrow .section composed of a pair of gangs 7, 8 of any approved type. a rear frame designated as a whole by the reference numeral 9, a rear barrow section composed of a pair of gangs 10, 11, and a draft connection through which the rear barrow section is operatively connected with the front frame so as to he drawn thereby, composed principally of a pair of parallel draft bars 12, 13 connected with the front frame and cross-connected toward their rear ends by a curved bar 111-, the ends of which are firmly secured to thc draft bars 12. 13, as by bolts 15 shown in Fig. 2. So far as may be necessary to a clear understanding of my invention. the parts above referred to will be more specifically hereinafter described.

The front frame 6 preferably comprises two longitudinally disposed bars lo'. 17 spaced apart and suitably braced together. and having at their forward ends a cleris 1.8 or other lsuitable means for connecting thc barrow to a tractor, or to a (cam, as may be preferred. ln the arrangement shown in the drawings, and particularly in Fig. l. the forward ends of the bars 1G, 1i' are bent downward, as shown at 19, and lthe clevis 18 is secured to this downturned portion, which also has hinged to ita support 2() which mav be turned down to the position shown in full lines in Fig. 1 to support the forward end of the front frame, or may be swung back to the position shown in dotted lilies in said ligure, when it may be held up by a hook 2l. Secured to the forward portions of the bars 16, 17 are diagonal braces 22. 23, the rear ends of which are connected with a trans versc frame member in the form of a beam 24, which is also secured to the rear end por tions of the bars 1G, 17. The end portions of the beam 24; are bent dowmvard and backward, and are adjustably connected by vertically disposed bolts 25. 2G with bearing brackets 27, 28 carried by the gangs 7, 8 respectively. The bolts 25, 26 serve as vcrlUU moved forward or backward.

`tical pivots about which the` gangs 7, 8 "re spectively swinglwhen they are adjusted to varythcir angular relation toV each other. At "their inner ends the` gangs 7,98 are provided with the `usual end thrust members in the form of convex' bearing surfaces 29, 30 which bear against each other, as shown in Fig. 2, and adjacent to their inner ends said gangs are provided with brackets(k 31. 3

connected respectively by'links 33, 34 with a vertically disposed lever 35, by `the rocking of which the inner ends of the gangs may be which is bifurcated, as shownin Fig. 2, is

fulcrumed between its endson bolts 36 supported by are secured braces 37, the lower endsof which to the bars 16, 17, respectively,

while their upper ends are secured to stand` ards 38, as shown in Fig. 1. Pivotally mounted between the upper ends of the' standards 38 isa collar 39 through which exf tends a screw-threaded shaft 4() `adapted to rotate ,therein but held thereby against end wise movement. On said shaft is mounted an internally threaded collar 41 `which is pivotally connected by links 421 with the upper ends of the members of the lever A crank 43 on the shaft 40 provides means for rotating it, so that by rota-ting said shaftv the collar 41 may be moved along it, there-y by actuatingthe lever 35 and angu'larly ad justing the( front gangs. `The shaft 40 and collar 41 also serve to lock the gangs in their different positions of adjustment. The inner ends ofthe front gangs `maybe vertically ad-` justed to `regulate theirpenetration by means of a crank 44, shown in Fig. 1, in a manner well known to those familiar with the art. The front gangs areprovided with the usual horizontal scraper-carrying bars 45,46, best to be capable of swinging laterally orapproximately about a vertical axis, as well asof swinging vertically, anclalso sonas to permit the rearframe to rock to some ei;- tent about an axis extending longitudinally of the harrow so that the opposite rear gangs may accommodate themselves to in-v equalities in the ground, as is usual `in liar# rows of this type. In the illustratedl construction these several movements are provided for by means which will now be described. By reference to Figs. 2 and 3 will be seen that thedraftbars 12, 13 are The lever 35, bolts l5.

connected at ytheir] forward ends pivotally horizontal with the transverse beam 24a-'by rbolts 47, 48, and consequently may swing vertically. `Said bars 12, 13, which are preferably-made of angle iron, are placed equally distant from and at oppositer sides of the median line of the front harrow section, and lare held in parallelism with such median line by the `curved bar 14, which is syinmet-A ricallydisposed relatively to said bars with its convex surface toward the front, andis fixedly secured thereto at its ends byA the The bars 12, 13, togetherwiththe curved barI 14, constitute a supplemental draft frame which is capable ofl swinging vertically about the pivot bolts 47, 4S, and,

as will hereinafter appear, the curved bar which the draft applied to the front frame is transmitted to the rear frame 9, and through it to the gangs 10, 11` oftherear v14 functions as a rocker bearing through harrow section; 4The pivotal connections atk `tlie`froiit ends of the `bars V12, 13k may be vinafde loose enough to permit either of the rear gangs to rise or fall tosome extent independently of the other, so that said gangs ni ay ties in the ground, or ythe flexibility of the draft frame may be relied on to permit such D movement. i

The frame `of the yrear barrow section comprises` a transverse beaiir 49 which is similar to the beam24, and is similarly connectedto the rear gangs` as will be hereinafter described, and also a bar 50, arranged forward of and preferably parallel with the beam 49 andj'provided with a. curved central portion orV member 51,which is preferably an `integral kpart of saidA bai' and extends horizontally' across Vthe bars 12, 13 in front ofthe 4curvedibar 14. The endportionsof end portions of the beam 49 by bars .50 and braces'lll".

The rearward surfaceof `the member 51 is made convex, its curvature being the same as that of the front surface of the bar 14 against which it is adapted to bear, so that the 'iiieiiiberslll and 51 cooperatewith each other to form arocking draft connection betweenthe front and rear frames, and therejfore between the draft transmitting devices' and the rear harrow section, through which draft force is transmitted to the rear sec-` Ytionby a pushing operation.v The arrangement` such` that when the front and rear harrow sections are in position for straightaway work, at which time the beams 24 and 49 will be parallel with each other, the ceni ters of the convex surfaces of the bar 14 and member 51 will be inr Contact with each other, and this point of contact will liey in the median line of the harrow. When, however,` the harrow sections are swung to an angular position relatively to each other,

accommodate themselves tol inequali- .the bar 5() are rigidly connected with the p lill as in turning tlieliarrow in one direction or the other from a straight-ahead position, the curved bar 14 will swing in the saine direction as the front harrow section, and by rocking on the men'iber 51 will cause the point of contact between the convex surfaces of said members to travel toward the side of the harrow opposite that toward which the front section is turned, or, in other words, toward the outside of the curve through which the barrow is being tui'ned. For example, if the liarrow is turned to the left, as illustrated in Fig. Si, the front and rear liarrow sections will assume a, position similar to that illustrated in said ligure, and the point of Contact between the members 14C and 51 will travel to the right a greater or less` distance. depending on the degree of curi'ature of said members and the sharpness ot the tuin that is being negotiated by the barrow. A similar shifting of the point of contact of tlie'nienibers 14 and 5l occurs whenever for any reason there is any lateral or angular movement of the liarrow sections relatively to each other. As in making ay turn, as well as when the rear section swings laterally, the ycenter of load represented by the rear liarrow section shifts toward the outside of the curve, or in a direction opposite. that in which said section swings, it will he apparent that by the arrangement described under either of such conditions the point of application of the draft to the reai' harrow section shifts in the saine direction as the center of load.` and consequently the draft operates effectively to restore the, rear liarrow section to its .normal or straightaway position. As soon ,as the latter position is reached, the. contacting point of the members 14 and 51 is again brought into coincidence with the median line of the harrow and the line of draft coincides with the center of load. Any deviation of the front'I and rear harrow sections from their normal. posit-ion, therefore, brings the force of the draft into pla y towaid restoring the sections to their normal position, and accordingly the draft force is always effective as a stabilizing factor and resists any tendency of the rear liarrow section to swing laterally, or to side slip or drift on side hill work. In this connection it should also be noted that when the front liarrow section is turned from a straight-away position, the action of the members 14 and 51 causes the center of uniss of the rear harrow section tobe moved up closer to the front hai-row section. This relative forward movement of the rear section of course requires the expenditure of draft force, owing to the resistance of the rear gangs, which gives them a. tendency to lag, and consequently whenever the harrow is turned laterally in either direction the resistance of the rear barrow section tends to restore both sections to their straightaway position, and incidentally to swing the members 14; and 51 so as to bring their point of contact to the median line ot the barrow, at which time the front and rear sectionsk tion, cooperate to restore the liarrow sections` kto their normal position whenever there is any deviation froni such position. 'lhe harrow is therefore essentially stable, or not nervous. The degree of curvature olI the members 14 and 51 may vary within rather wide'liniits. but I prefer to use compara-4 tively flat curves because of the greater degrec of stability thereby realized.

Registration of the disks of the front and rear sections combined with the stabilizing characteristics above described is liest ohtained by making the curved contacting sur faces of the members l-t and 5l similar arcs of an ellipse, and locating said nicinbers so that the point of contact of such surfaces is always equi-distant from the transverse axes of the front and rear harrow sections. and

coincides with the median line of the barrow' when the liaii'ow sect-ions are in their normal position. By the transverse axis of a harrow section is meant a horizontal line per pendicular to the median line of such section and intersect-ing the longitudinal centers of the two gangs constituting such section. (')bviously when the liarrow sections arc in their norinal position,- for straight-away work, their transverse axes are parallel. and to secure registration the front and rear scc tions should be so connected that whenever they deviate from a straight-away or parallel position, as in rounding curves or turning corners, both sections swing through the arc of a circle the axis or center of which determined by the point of intersection of their respective transverse axes projected. and the radius of which may be measured along either of said transverse axes from such center to the center of the median line ol either liarrow section. By making the curved surfaces of the nicnihers 14 and 51 similar arcs of an ellipse, and locating said members so that their point of contact when the barrow sections are in their normal position is midway between the front and 4rear transverse axes of said sections, such midway position will not be affected by lateral shift ing of their point ot' contact incident to turning or lateral swinging of the harrow sections, as such point of contact will move along a linel substantially bisecting the angle of convergence of said sections. 'l'lie movenient of said sections requisite to maintain registration will therefore he brought about. and, at. the same time. as such movement of the point of Contact is inverse, i. e., away from the point of convergence when the sections are moved from a position of parel` maintain stability, as hereinbefore described.

y I wish it to be understood, howeveiythat al though the best results as to maintaining registration are obtained by the equi-distant positioning of the point of Contact as above described, considerable variation is permis- 1 sible where a. high degree of accuracy Vis not required, and therefore my invention is not y limited to mathematical exactness in that respect. From the foregoing it will be manifest that the members 14 and 51 constitute y controlling means which functions to pivotally connect the front and rear harrow sec-` tions together so that the rear section is v are held relatively to each other so that the disks of corres iondin T front and rear danos ,tu C ci always maintain registration whether the harrow be moving str: ight ahead or be malrcaused to swing laterallyrelatively to thel front section, and that s: id controlling means ing a turn, or the rear section otherwise be also functions to cause the point of application of the draft to the rear section to move laterali relatively to the line of advance when tie rear section swings laterally, or when the barrow sections are angled relativelyto each other in making a turn, such lateral movement of the point of application of the draft being in a direction inverse to that of the turn, so'that the draft acts directly to restore the sections to parallel relation to each other, as well as to resist angling of the harrowsections when they are parallel.

Up to this point the parts described are l the same as those shown and described in the `said Hand application, and such construction is not separatel claimed as of my heen suggested, has to do with improved means for holding the curved members 14 ,and 51 in proper working relation to each other under ordinary operating conditions, and also to hold said members together in backing the harrow. F or this purpose one of the members 14 or 51, preferably the latter is provided centrall with ka rearwardly projecting block 52 fixe ly secured thereto by bolts 53, as best shown in Fig. 5, so that its longitudinal center line lies in the median line of the rear unit.

The block 52 is in generalwedge shaped,

its side margins being similarly curved in convex form and merging to a blunt point at the rear `where said block is provided with a lug 54 which extends upward above the horizontal plane of the curved bar 14. The

upper surface of the block 52 lies immedi-i ately `under said bar and it projects between two guide plates 55, 56 secured to the curved member 14 at opposite sides of the b10ck`52 and inthe same horizontal plane assaid iurpose ofA which is to allow space for the lock 52 to swing Fig. 5. y y i The normal position of these parts is shown in Fig. 2,.from aninspection of which it will be seen that when the front and rear units are in position for straight-away work, at which time the centers of the' members 14 and 51 are in contact with each other, the longitudinal axis of the block 52 lies in the median` line of the barrow., and its side margins bear against the inner margins of the guide plates 55, 56 at diamet-rically opposite points. At this time the lug 54 lies some distance back of the rear margin of the member 14, as shown in Fig. 2. l/Vhen the parts are in this position, the members 14, 51 are held against endwise movement relatively toeach' other by the engagement of the block 52 with the guide platesl 55, 56, but rocking of said members on eachother is notinterfered with by said parts. If the harrow be backed, the backing power will be applied to the laterally, as indicated in front unit and will cause the member 14 to 55, 56, and will swing betweensaid guide platesto one side or the other, as illustrated in said figure. During this movement of the block 52 it still continues to` hold the members 14, 51 against relative endwise movement, since one margin of said block engages one of the guide plates, as 55, and the other margin of said block engagesthe other guide plate, as clearly sliowiiin said figure. This rocking movement of the block 52 moves the lug 54 toward the member 14, but said block is located soV that when the parts are in normal position it lies far enough back of the member 14 so that the necessary fore and aft movement of said block is permitted to allow the block' 52 to roclr to the Vdesired extent. It will be understood, of course, that the curvature of the side margins of the block 52 shouldbe correlated with that of the members 14 and l, so that proper contact between the several bearingk surfaces in the different positions which the parts assume will-be maintained. It is not necessary, however, that the members 52, 55 and 56 be fitted together with a high degree of accuracy, as so nsV llO

. long as such parts cooperate to prevent any considerable relative endwise movement of the members 14C and 51 that is all that is necessary.

While I prefer to make the bearing surfaces of the members let and 51 elliptical, that is not necessary, as they may be variously curved, and an important advantage ot' providing for holding said members against relative endwise movement by the devices above described is'that by that means a wider range of variation in the curvature of' the members 14 and 51 is permitted.

In the harrow illustrated the side bars 12, 13 are preferably cross-connected by a transverse brace 58 and by a pair of crossed braces 59, 60, as best shown in Fig. 2, thereby strengthening the liront draft frame. lt will be understood that the rear gangs 10, 11 are mounted so as to be angularly adjustable in the same manner as the front. gangs, and while such adjustment has nothing to do with the novel features which form the subject mattei' ot this application, it may be .explained that the gangs 10, 11 are mounted to swing about vertical pivots (51, said pivots being mounted in the end portions ot the rear frame 9. Angular adjustment ot said gangs is elt'ected by means of bars G2 pivotally connected with the inner end portions of said gangs, and also connected `with the end portions of a transverse frame (53 arranged to slide longitudinally on bars G4 secured to the members 49, 50 of the rear frame, as shown in Figs. 1, Ll and 5. Preterably the bars (32 extend over stirrups (35, (36 secured to the frame (53, as shown in Fig. 1. rlhe frame G3 is movable fore and aft to correspondingly move the inner ends of the gangs 1t), 11 by means ol a screw-threaded shaft 67 held against longitudinal movement; by a plate G8, shown in Fig. 4, and working in a threaded sleeve (39 carried by the frame (52. The forward end of the shaft 67 is connected by a universal coupling TO with a rod 71 that extends forward, and preferably through the screw-threaded shalt ,40 in which it turns lreely and is movable longitudinally to conipensate for the 'loro and aft movement of the rear section relatively to the liront section incident to turning movements of the harrow, as herinbet'ore described, the forward end ot said rod 71 being provided with a crank 72 by which it may be rotated. The shaft G7 serves not only to adjust the angular position of the rear gangs, but also holds them in position when adjusted. Any other suitable means may, however, be employed for adjusting the several gangs angularly, as my invention contemplates the application of the improvements hereinbefore described by which registration and stability are obtained to any of the various forms of tandem disk hai-rows comprising front and rear sections flexibly coupled together, regardless ol. differences in design of such harrows in other respects.

What I claim as my invention and desire to secure by Letters Patent, is

1. A tandem disk harrow comprising front and rear diskcarrying units, and draft trames coupling said units,` together to pcrmit lateral swinging thereof with respect to each other about points lying between the transverse axes of said units and actuated by movement of said transverse axes toward or from a position of parallelism to shift the point of application ol' the draft to the rear unit inversely laterally, and means rigid with one of said draft frames and engaging the other draft trame lo prevent substantial endwise movement ol' said lrames relatively to each other.

2. A tandem disk harrow comprising front and rear disk-carrying units, and dral't lrames coupling said units together to permit laici-al :-\v1nging thcl'eol with respect to cach other aboutpoints lying between lhe transverse axes ot said units, means actuated by movement of said transverse axes toward or from a position of parallelism to shift the point ot application ot' the draft of the rear unit inversely laterally, and means rigidly connected with the trame ot' one of said units and engaging the trame ot the other unit to prevent substantial cndwise movement ol lsaid trames relatively to each other.

il, A tandem disk harrow having l'ront aml rear disk-carrying units arranged to be angled relatively to each other, draft connections between said units comprising means actuated by movement ol the transvcri-e axes ot' said units from a position of parallelism to nieve said rear unit toward said trent` unit and to shil't the line of the dra'lt applied to the rear unit laterally away from the point ot convergence ol said transverse axes projected. and means rigid with one of said drat't crnmectimls and engaging The other dralit connection to prevent sulstantial transverse movement thereof relatively to each other.

l-. A tandem disk harrow having front and rear disk-carrying units arranged to be angled rclatively to cach other. iransvcrscly rocking couplixmr devices between said units connected with said rear unit forward ot' their connection with the 'front unit for shifting the line of draft applied to the rcar unit inversely laterally when .said units movc angularly relatively to cach other. and means rigidly connected with one ot .said coupling devices and engaging thc other coupling device to prevent substantial transverse movement oli said coupling devices rela tively lo each other.

5. A tandem disk harrow comprising a. l'ront disk-carrying unit, a rearwardly cx tending frame connected therewith, a rear 13 diskscarryfing `unit having -`a 'forwardly extending frame, said units being adapted to `be `angled relatively'to each other, front and site to that in which said -nnits swliiig, .and

means rigidly connected with `one of said `draft members and `:engaging :the :other draft member to prevent substantial endwise movement of said frames relatively to each other.

G. A tandem disk harrowcomprising a front dislccarrying unit, La rearwardly ef;-

tending frame connected therewith, a rear disk-carrying unit having a Vforwardly.eX-

tendrngframe, said units being adapted to` be angled relatively to each other, opposite'ly curved rocker bearingswcarried by said frames respectively, the rocker bearing carried bythe .front frame be'rngiiin rear :of that carried .by the rear frame, and means rigidly connected with one of Vsaid rocker bearings i `and `engaging the `other `rocker shearing to prevent substantial endwise movement of said rocker bearings relatively L[to each other.

l7. A `tandem disk harrow comprising a front disk-carrying unit, a rearwardly/extending `frame co Mtherewith, a rear disk-carrying unit having a forwardly extending frame, said units being adapted to be angled relatively to each other, oppositely curved rocker bearings carried by said frames respectively, the rocker bearing carried by the front frame being in rear of that carried by the rear frame, and a block rigidly connected with one of said rocker bearings and guided by the other rocker bearing for preventing substantial endwise movement of said bearings relatively to each other.

8. A tandem disk harrow comprising a front disk-carrying unit, a rearwardly eX- tending frame connected therewith, a rear diskrarrying unit having a forwardly eX- tendingframe, said units being adapted to be angled relatively to each other, oppositely curved rockerbearings carried by said frames respectively, the rocker bearing carried by the front frame being in rear of that carried by the rear frame, and a block rigidly connected with one of said rocker bearings and adapted to rock between fixed guides carried by the other rocker bearingy to prevent substantial endwise movement of said bearings relatively to each other.

9. A tandem disk harrow comprising a front disk-carrying unit, a rearwardly extending frame connected therewith7 a rear disk-carrying unit having a forwardly extending frame, said units being adapted to be angled relatively to each other, oppositely curved rocker bearings carried by said frames respectively, the rocker bearing carried fthe front frame being in rear of Vthat carried by the rear frame, a block :rigidly connected with the front rocker bearying .and projecting rearwardly therefrom, ,and guiding means Acarried by the rear `rocker bearing and cooperating with said :block to Vprevent substantial endiwise fm'ovement of :said rocker bearings relatively to each other.

l0. A tandem disk harrow comprising a front disk-carrying unit, a .rearwardly eX- tending frame connected therewith, a :rear disk-carrying unithaving a forwardly extending frame, said units Ibeing adapted to be .angled relatively to each other, oppositely curved rocker bearings carried :by ysaid frames respectively, the rocker :bearing .carried by the front` `frame being in rear .of that carried by the rear frame, .a block rigidly connected with the front rocker bearing and .projectingrearwardly therefrom, said block having oppositely disposedconvex side margins, and guiding means carried by the rear rocker bearing and cooperating `with said block to prevent substantial endwise :movement of said rocker bearings relatively to each other.

ll. .A tandem disk harrow comprising front and rear disk-carrying units,sand draft frames coupling said unitsl together V-to `permit lateral swinging thereof'with respect to i each other about points lying between the transverse axes of said units and actuated by movement of said transverse axes toward or from a position of parallelism tov shift the point of application of the draft to the rear unit inversely laterally, means rigid with one of said draft frames and engaging the other draft frame to prevent substantial transverse movement of said frames relatively to each other, and means for holding said draft frames approximately together when the harrow is backed.

12. A tandem disk harrow having front and rear disk-carrying units arranged to be angled relatively to each other, draft connections between said unit-s comprising means actuated by movement of the transverse axes of said units from a position of parallelism to move said rear unit `toward said front unit and to shift the line` of the draft applied to the rear unit laterally away from the pointof convergence of lsaid transverse axes projected, means rigid with one of said draft connections and engaging the other draft connection to prevent substantial transverse movement thereof relatively to each other, and means for holding said units approximately together when the harrow is backed.

13. A tandem disk harrow having front and rear disk-carrying units arranged to be angled relatively to each other transversely rocking coupling devices between Cil for ehifting the line of draft applied to the rear unit inversely laterally when said units,

move angularly relatively to each other, means rigidly connected with one of said coupling devices and engaging the other coupling device to prevent substantial transi verse movement of said coupling devices relkmit lateral swinging thereoic with respect to each other about points lying between the transverse axes ot said units` and actuated by movement ol' said transverse axes toward or from a position of' parallelism to shilt the point ot' application ot the draft to the rear unit inversely laterally, and means rigid with one ot' said draft frames and engaging the other draft 'trame to prevent substantial endwise movement o said trames relativelyv to each other and to hold said couplingr devices approximately together when the harrow is backed.

15. A tandem disk barrow comprising a front disk-carrying unit having a rearwardly extending frame, a rear diSkcarry ing unit having a forwardly extending frame, said units being adapted to be angled relatively to each other, oppositely curved rocker bearingscarried by said frames respectively, the rocker bearing carried by the front trame being in rear of that carried by the rear frame, and means rigidly connected with one of said rocker bearings and engageing the other rocker bearing to prevent substantial endwise movement ol said rocker bearings relatively to each other and to hold said rocker bearings approximately together when the barrow is backed.

1G. A tandem disk barrow comprising a front disk-carrying unit having a rearwardly extendii'ig frame, a rear disk-carrying unit having a forwardly extending trame, said units being adapted to he angled relatively to cach other, oppositely curved rocker bearings carried by said frames re spectively, the rocker bearing carried by the front trame being in rear of that carried by the rear frame, and a block rigidly connected with one ol said rocker bearings and guided by the other rocker bearing for preventing substantial endwise movement of said bearings relatively to each other, said block having a lug for preventing excessive separation ol said rocker beiu'ings when the barrow is ba cke d CHARLES H. YVHITE. 

